The application relates to a process for the separation of a glycol from an electrolyte-containing aqueous solution.
The application relates in particular to a process for the separation of a glycol from an electrolyte-containing aqueous solution by separating a fraction, the glycol: electrolyte ratio of which has been raised, from the solution by means of a semi-permeable membrane and subsequently recovering the glycol from said fraction. Such a process is known from UK patent specification No. 1463324. It describes how ethylene glycol can be recovered from salt-containing waste water from plants for the preparation of ethylene oxide according to the direct oxidation process by subjecting the waste water charged with salt and glycol to reverse osmosis through a semi-permeable membrane using pressure. According to said process something over 60% of the glycol present in the waste water can be recovered; the remainder has to be either discharged, together with a concentrated salt solution, as a waste stream, or worked-up further at high cost.
It has now surprisingly been found that it is possible to attain a more intensive separation of a glycol from an electrolyte-containing aqueous solution when the solution containing both glycol and electrolyte is subjected to electrodialysis.